Antennas used in early cellular base stations typically did not include means for varying antenna beam direction and had to be mounted to a support structure at an inclination required to provide a beam producing the required cell coverage. More recent antennas have included means for remotely adjusting downtilt of the beam of an antenna of a cellular base station. WO96/14670 discloses an antenna having mechanically adjustable phase shifters which produce variable electrical phase shifts in the feed path of the antenna to effect downtilting of the beam of an antenna.
Phased array antennas, used in radar applications, provide both azimuth beam steering and vertical beam tilting (downtilt) to direct the beam of an antenna in a required direction. Such antennas have typically employed active switching elements and been of complex and expensive construction.
If more than one characteristic of the beam of an antenna of a cellular base station could be varied, cellular communication systems could be more flexible in allocating capacity to desired areas.
The applicant's prior application WO96/14670 discloses an antenna control system for remotely adjusting the downtilt of a plurality of antennas. The controller 80 is located at the base of a cellular base station and a separate cable 78 is required to control each antenna. This requires a new control cable 78 to be run from the mast head to controller 80 each time a new antenna is added.
In the system of WO96/14670 each antenna is identified by the port to which cable 78 is connected. The number of antennas that may be controlled by a controller 80 is limited by the number of available ports.
Prior art systems have utilised proprietary controllers to remotely adjust antenna characteristics. It would be desirable to enable standard devices that are widely available to be utilised to program and control the antenna control systems.